Blood test apparatus and blood test method

ABSTRACT

A blood test apparatus has a housing with an opening, and a plunger that moves back and forth inside the housing, the plunger having a projecting member. A fixing member fixes the plunger, which is provided in the housing. A blood sampling cartridge, in which a blood sensor, a puncturer, and a holder that holds the blood sensor and the puncturer, are integrated. The blood sampling cartridge is removably attached to the opening. The puncturer includes a lancet, one end of which is held by the plunger, and a blood collection needle attached to an other end of the lancet. A measuring circuit measures a signal obtained from the blood sensor to analyze components in the blood.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 12/162,627,filed Jan. 31, 2007, which was the National Stage of InternationalApplication No. PCT/JP2007/051627, filed Jan. 31, 2007.

TECHNICAL FIELD

The present invention relates to a blood test apparatus and a blood testmethod.

BACKGROUND ART

Conventionally, as an apparatus for measuring the blood sugar level, anapparatus combining a puncturing device for making a scar on a fingertipand a measuring device attached with a disposable blood sensor forsampling a small amount of blood squeezed from the fingertip where thescar is made, is widely used.

However, if such a puncturing device and a measuring device are providedseparately, the patient needs to puncture the skin with the puncturingdevice and then sample blood using the measuring device, which makes themeasuring operation complex.

Therefore, a blood test apparatus that integrates a lancet with apuncturing needle and a measuring device to which a blood sensor isattached, is proposed (see Patent Document 1). As shown in FIG. 13,proposed blood test apparatus 1 has cylinder-shaped housing 2, plunger 3that moves back and forth inside housing 2, lancet 4 that has one end 4a held by plunger 3 and the other end 4 b attached with blood collectionneedle 5, and blood sensor 6 attached to one end 2 a of housing 2.

Test steps using blood test apparatus 1 will be described. First, bloodsensor 6 is made to abut on skin 7, which is the part to be punctured,of the patient. Next, latch convex part 9 a of handle 9 connected toplunger 3 and latch concave part 2 b formed on housing 2 are disengaged.Plunger 3 urged by spring 10 is thereby propelled in the direction ofarrow 8. In response to this, lancet 4 held by plunger 3 and bloodcollection needle 5 attached to this lancet 4 are also propelled in thedirection of arrow 8.

Propelled needle 5 goes through blood sensor 6 and makes a tiny scar onskin 7. The blood flowing out from this scar is detected by a detectingsection of blood sensor 6. A signal obtained according to the glucose inblood is led to measuring circuit 12 from connection electrode 6 a viaconnector 11. Measuring circuit 12 calculates the blood sugar level ofthe sampled blood and displays the calculation result on display section13.

-   Patent Document 1: Japanese Patent Application Publication No.    2003-524496

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

In the test using the blood test apparatus, the blood flowing out fromthe skin punctured with blood collection needle 5 is preferably sampledmore easily into blood sensor 6, and preferably flows out from the skinimmediately after puncturing. Therefore, a vacuum pump may be providedin the blood test apparatus to create a negative pressure around thepart to be punctured on which blood sensor 6 abuts.

However, when blood is tested using the blood test apparatus providedwith a vacuum pump and the like, the patient holds the apparatus withone hand, presses blood sensor 6 against the skin, operates the switchfor driving the vacuum pump, and performs the operation for releasinghandle 9 to propel lancet 4. Therefore, the apparatus is difficult to behold stably and is likely to miss from the part of the skin to betested, which may make adequate measurement difficult.

Means for Solving the Problem

The blood test apparatus of the present invention has a housing with anopening, and a plunger that moves back and forth inside the housing, theplunger having a projecting member. A fixing member fixes the plunger,which is provided in the housing. A blood sampling cartridge, in which ablood sensor, a puncturer, and a holder that holds the blood sensor andthe puncturer, are integrated. The blood sampling cartridge is removablyattached to the opening. The puncturer includes a lancet, one end ofwhich is held by the plunger, and a blood collection needle attached toan other end of the lancet. A measuring circuit measures a signalobtained from the blood sensor to analyze components in the blood. Whenthe blood sampling cartridge is attached to the opening of the housing,the projecting member of the plunger is engaged with the fixing member,such that the plunger is fixed with the fixing member.

Advantageous Effect of the Invention

According to the blood test apparatus of the present invention, bypressing the blood sensor against the part to be punctured, a negativepressure means can start automatically. Therefore, in the blood test,the negative pressure means can start even if the patient does notperform special operation.

Further, by puncturing the skin plumped up by the negative pressurecreated by the negative pressure means around the part to be punctured,it is possible to sample blood in a simple manner and perform testreliably.

Further, the negative pressure means starts after the part to bepunctured is detected, so that it is not necessary to drive the negativepressure means before the part to be punctured is made to abut on theblood sensor. Therefore, battery life can be extended by reducing powerconsumption for driving the negative pressure means, so that it ispossible to realize a blood test apparatus that particularly excels inportability.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagrammatic perspective view of a blood test apparatus inuse;

FIG. 2 is a cross-sectional view of the blood test apparatus;

FIG. 3A is a cross-sectional view showing the main part before a bloodsampling cartridge is attached to an attaching part of the blood testapparatus;

FIG. 3B is a cross-sectional view showing the main part when the bloodsampling cartridge is being attached to the attaching part of the bloodtest apparatus;

FIG. 3C is a cross-sectional view showing the main part when the bloodsampling cartridge is attached to the attaching part of the blood testapparatus;

FIG. 3D is a cross-sectional view showing the main part when a bloodsensor of the blood sampling cartridge attached to the attaching part ofthe blood test apparatus is forced into the blood test apparatus by thepart to be punctured;

FIG. 3E is a cross-sectional view showing the main part when the bloodsensor of the blood sampling cartridge attached to the attaching part ofthe blood test apparatus is forced into the blood test apparatus by thepart to be punctured plumped up by a negative pressure;

FIG. 3F is a cross-sectional view showing the main part when the part tobe punctured that is abut on the blood sensor of the blood samplingcartridge attached to the attaching part of the blood test apparatus, ispunctured;

FIG. 3G illustrates a state where the fixing of the lancet fixed by afixing claw of the blood sampling cartridge is released, and is across-sectional view showing a state before the fixing is released;

FIG. 3H illustrates a state where the fixing of the lancet fixed by thefixing claw of the blood sampling cartridge is released, and is across-sectional view showing a state after the fixing is disengaged;

FIG. 4 is an assembly drawing of the blood sampling cartridge;

FIG. 5A is a cross-sectional view of the blood sampling cartridge, andshows a state upon puncturing;

FIG. 5B is a cross-sectional view of the blood sampling cartridge, andshows a state after puncturing;

FIG. 6 is a diagrammatic perspective view of the blood samplingcartridge;

FIG. 7 is a cross-sectional view of the blood sensor;

FIG. 8A is an exploded plan view of the blood sensor and shows a cover;

FIG. 8B is an exploded plan view of the blood sensor and shows a spacer;

FIG. 8C is an exploded plan view of the blood sensor and shows asubstrate;

FIG. 9 is a perspective plan view of the blood sensor;

FIG. 10 is a perspective plan view of another example of the bloodsensor;

FIG. 11 shows a flow of the blood test using the blood test apparatus;

FIG. 12 is a block diagram of the blood test apparatus; and

FIG. 13 is a cross-sectional view of the conventional blood testapparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows an appearance of one example of the blood test apparatus.That is, FIG. 1 shows a state where the patient holds blood testapparatus 20 with the right hand and tries to sample blood from theindex finger of the left hand. In FIG. 1, cylinder body 21 a is formedon one side of housing 21. Blood sampling cartridge 22 with blood sensor24 is attached to opening part 21 b of cylinder body 21 a. Housing 21also has display section 75.

FIG. 2 is a cross-sectional view of one example of the blood testapparatus. As described above, blood test apparatus 20 has housing 21formed with resin. On one side of housing 21, cylinder body 21 a (forexample, having the shape of a cylinder) with opening part 21 b isformed. Blood sampling cartridge 22 is attached to opening part 21 b ofcylinder body 21 a.

Blood sampling cartridge 22 has a puncturing means integrated withholder 23 (for example, having the shape of a cylinder) and blood sensor24. Blood sensor 24 is attached to one end of holder 23. The puncturingmeans include lancet 25 that is provided slidably inside holder 23, andblood collection needle 26 that is attached to the other end of lancet25.

Although described in detail later, blood sensor includes detectionelectrodes and connection electrodes connected to the detectionelectrodes, and connectors provided in the blood test apparatus contactwith the connection electrodes.

Grip part 25 a formed at the other end of lancet 25 configuring bloodsampling cartridge 22 is held by holding part 30 a provided at one endof plunger 30 that slides in cylinder body 21 a. Handle 31 is connectedto plunger 30. Latch convex part 31 c is formed at one end 31 b ofhandle 31. Handle 31 goes through hole 21 c formed in housing 21 and islatched by the joint of latch convex part 31 c and latch concave part 21d.

Puncturing spring 28 urges plunger 30 and lancet 25 included in bloodsampling cartridge 22 attached to plunger 30 in the direction of theneedle tip. Holder pressing spring 29 urges holder 23 and blood sensor24 attached to holder 23 out of blood sampling cartridge 22 attached tocylinder body 21 a, in the direction of the needle tip. Slider 37 holdsholder pressing spring 29 and slides inside cylinder body 21 a.

The blood test apparatus of the present invention has the first sensingmeans that detects that the part to be punctured is located in anappropriate position. Here, the “appropriate position” means an openingpart of the housing in which the puncturing means is arranged. The firstsensing means in FIG. 2 is mechanical switch 38 provided inside cylinderbody 21 a. When holder 23 moves in a direction to be immersed incylinder body 21 a, mechanical switch 38 is pressed by slider 37.Therefore, mechanical switch 38, which is the first sensing means, isnot driven unless blood sampling cartridge 22 is attached.

Further, measuring circuit 32 is housed at the side of one side 21 e ofhousing 21. Measuring circuit 32 connects with connectors (describedlater) formed in cylinder body 21 a. Further, battery 34 that suppliespower to measuring circuit 32 is also arranged in the blood testapparatus of the present invention.

The blood test apparatus of the present invention has a negativepressure means. The negative pressure means of the blood test apparatusin FIG. 2 is vacuum pump 82. The output of negative pressure means 82 isconnected to inside cylinder body 21 a via negative pressure path 83.Therefore, negative pressure means 82 can create a negative pressure incylinder body 21 a and holder 23 of blood sampling cartridge 22.

FIG. 3 is an exploded cross-sectional view showing blood samplingcartridge 22, and the periphery of opening part 21 b of cylinder body 21a to which blood sampling cartridge 22 is attached.

FIG. 3A shows a state before blood sampling cartridge 22 is attached toopening part 21 b of cylinder body 21 a. Holder 23 and lancet 25 ofblood sampling cartridge 22 are fixed to each other with fixing claw 23f. Grip part 25 f is formed in lancet 25.

On the other hand, in cylinder body 21 a, plunger 30 is provided to beslidable in front and back directions (in this figure, in right and leftdirections). Plunger 30 has holding part 30 a that holds grip part 25 fof lancet 25. Further, plunger 30 has projecting part 30 b and is fixedby the joint of projecting part 30 b and plunger fixing member 31 fprovided in cylinder body 21 a. Plunger fixing member 31 f interlockswith button 31 g. When button 31 g is pressed, plunger fixing member 31f engages with projecting part 30 b provided in plunger 30 and fixesplunger 30.

Further, slider 37 is provided in cylinder body 21 a to be slidable infront and back directions (in this figure, in right and leftdirections). Slider 37 is urged by holder pressing spring 29 towardopening part 21 b. Mechanical switch 38-1 provided inside cylinder body21 a is pressed by slider 37 which has moved toward inside cylinder body21 a. As described later, mechanical switch 38-1 detects that the partto be punctured is located in an appropriate position. Positioning thepart to be punctured in an appropriate position includes, for example,positioning the part to be punctured so as to contact with opening part21 b.

FIG. 3B shows a state where blood sampling cartridge 22 is attached tocylinder body 21 a from opening part 21 b. When blood sampling cartridge22 is inserted into cylinder body 21 a in the direction of the arrow,button 31 g is pressed, and thereby plunger 30 is fixed with plungerfixing member 31 f.

FIG. 3C shows a state where blood sampling cartridge 22 is attached toopening part 21 b of cylinder body 21 a of the blood test apparatus.Holding part 30 a of plunger 30 holds grip part 25 f of lancet 25configuring blood sampling cartridge 22. Further, in blood samplingcartridge 22, holder 23 engages with slider 37 attached in cylinder body21 a. Blood sensor 24 of attached blood sampling cartridge 22 isarranged in a state blood sensor 24 projects through opening part 21 bof cylinder body 21 a. Blood sensor 24 can be pushed back into openingpart 21 b against the urging force of holder pressing spring 29.

Blood sensor 24 of blood sampling cartridge 22 attached to cylinder body21 a and the puncturing means (including lancet 25 and blood collectionneedle 26) can operate separately. That is, lancet 25 of blood samplingcartridge 22 is driven by plunger 30. On the other hand, apart fromlancet 25, holder 23 and blood sensor 24 interlock with slider 37 andcan move in and out of housing 21 through opening part 21 b of cylinder21 a.

Further, the fixing of fixing claw 23 f (which fixes lancet 25) in bloodsampling cartridge 22 is preferably released when blood samplingcartridge 22 is attached to cylinder body 21 a. For example, as shown inFIG. 3G and FIG. 3H, it is only necessary to form supporting part 23 g,which is the center of rotation of fixing claw 23 f (and which may beformed by resin molding). FIG. 3G shows a state before the fixing offixing claw 23 f and lancet 25 is released, and FIG. 3H shows a stateafter the fixing is released. When holder 23 of blood sampling cartridge22 engages with slider 37, an end of slider 37 presses fixing claw 23 fso that fixing claw 23 f rotates (moves like a seesaw) using supportingpart 23 g as a supporting point. By this rotation, fixing claw 23 f isreleased from lacking part 25 g in lancet 25, and thereby the fixing isreleased.

FIG. 3D shows a state where the patient performing a blood test putsskin 7 of the part to be punctured (for example, the fingertip) to bloodsensor 24 at the tip of blood sampling cartridge 22 and forces bloodsensor 24 into opening part 21 b of cylinder body 21 a. That is, holder23 and blood sensor 24 move toward inside cylinder body 21 a byresisting the urging force of holder pressing spring 29, and stay whenblood sensor 24 matches opening part 21 b of cylinder body 21 a. As aresult, skin 7 of the part to be punctured contacts with opening part 21b of cylinder body 21 a, and opening part 21 b is covered. In the stateshown in FIG. 3D, mechanical switch 38-1, which is the first sensingmeans, is pressed to the first position by slider 37 which has moved.

When mechanical switch 38-1 is pressed to the first position, negativepressure means 82 starts and creates a negative pressure inside cylinderbody 21 a. Negative pressure means 82 preferably starts automatically.FIG. 3E shows a state where skin 7 of the part to be punctured is suckedin and plumped up in cylinder body 21 a to which a negative pressure iscreated by negative pressure means 82. By plumped skin 7 of the part tobe punctured, blood sensor 24 moves further toward inside cylinder body21 a. In the state shown in FIG. 3E, mechanical switch 38-1, which isthe first sensing means, is pressed to a second position by slider 37which has further moved. That is, mechanical switch 38-1 also functionsas the second sensing means that detects a change in the shape of thepart to be punctured by a negative pressure, i.e., detects a plumpnessof the part to be punctured. Further, the second sensing means may be adifferent member from mechanical switch 38-1. For example, a mechanicalswitch provided separately further behind (in the left in the figure)mechanical switch 38-1 in cylinder body 21 a, may be used as the secondsensing means.

After mechanical switch 38-1 is pressed to the second position by slider37, the part to be punctured is punctured. Therefore, display section 75preferably displays that mechanical switch 38-1 is pressed to the secondposition to encourage the patient to perform puncturing manually using apuncturing button and the like, or the apparatus preferably performspuncturing automatically after mechanical switch 38-1 moves to thesecond position.

FIG. 3F shows a state where skin 7 of the part to be punctured ispunctured. Plunger 30 moves toward the needle tip, and blood collectionneedle 26 projects from blood sensor 24 and punctures skin 7. In thisway, plunger 30 can move separately from holder 23.

After puncturing, plunger 30 is pulled backward and enters the stateshown in FIG. 3E, and blood is sampled from the skin of the patient andflows into blood sensor 24. As described later, by providing in bloodsensor 24, a detection electrode, which serves as a sensing electrode,it is possible to detect the inflow of blood. The inflow of blood ispreferably displayed on display section 75, or the negative pressuremeans preferably stops automatically after detection.

Mechanical switch 38-1 in FIG. 3 may be an electrical sensor or anoptical sensor. That is, when skin 7 of the part to be punctured forcesblood sensor 24 into opening part 21 b and thereby slider 37 moves,capacitance, electrical resistance, frequency, and the like, are changedand these changes are detected using an electrical sensor, or the lighttransmission rate is changed and the change is detected using an opticalsensor (such as a photo interrupter).

An electrical sensor utilizing electrical resistance (an electricalsensor of an electrical resistance type) is arranged inside cylinderbody 21 a in the same way as mechanical switch 38-1 shown in FIG. 3.Blood sensor 24 is pressed by part 7 to be punctured and moves towardinside cylinder body 21 a (leftward in FIG. 3). In response to this,slider 37 formed with conductive material moves to the position of theelectrical sensor of electrical resistance type and contacts with theelectrical sensor. The skin is detected based on the electricalresistance which changes by the contact.

The position where an electrical sensor utilizing capacitance (anelectrical sensor of a capacitance type) is arranged is the same as thatof the electrical sensor utilizing the electrical conductivity. Theelectrical sensor of the capacitance type has a pair of terminals anddetects the skin based on an electrical change between the terminals (inthis case, a change in capacitance). That is, blood sensor 24 is pressedby part 7 to be punctured and moves toward inside cylinder body 21 a. Inresponse to this, slider 37 formed with conductive material moves towardinside cylinder body 21 a and contacts with the electrical sensor of thecapacitance type. When slider contacts with both terminals of the pairof the electrical sensor, the capacitance between the terminals in apair changes. The skin is detected based on this change in capacitance.

The position where an electrical sensor utilizing a frequency change (anelectrical sensor of a frequency change type) is arranged is the same asthat of mechanical switch 38-1 shown in FIG. 3. The electrical sensor ofthe frequency change type incorporates a coil. When slider 37 formedwith conductive material approaches the coil to which a voltage isapplied, the resonant frequency changes by a change in the distancebetween slider 37 and the coil according to a change in the inductance.The skin is detected based on this change in frequency.

The position where the photo interrupter optical sensor is arranged isthe same as that of mechanical switch 38-1 shown in FIG. 3. Thereflective type photo interrupter optical sensor detects the skin byblocking light. That is, blood sensor 24 is pressed by part 7 to bepunctured and moves toward inside cylinder body 21 a. In response tothis, slider 37 formed with conductive material moves toward insidecylinder body 21 a and blocks the light of the light emitting element ofthe photo interrupter optical sensor. By the blocking of light, theinput of the light receiving element of the photo interrupter opticalsensor changes. The skin is detected based on a change in input of thelight receiving element.

[The Blood Sampling Cartridge]

Blood test apparatus 20 shown in FIG. 2 has blood sampling cartridge 22that incorporates and integrates lancet 25 to which blood collectionneedle 26 is attached and blood sensor 24. All the members included inblood sampling cartridge 22 can be attached to and removed from cylinderbody 21 a together. Therefore, blood sensor 24 and blood collectionneedle 26 can be attached and replaced in a simple manner.

Further, when blood sampling cartridge 22 is attached, blood collectionneedle 26 is accommodated in holder 23, so that blood sampling cartridge22 can be replaced securely without hurting the patient with bloodcollection needle 26 by error. Further, blood collection needle 26 isaccommodated in holder 23, and so the patient does not feel fear.Furthermore, blood collection needle 26 does not allow direct touch andso is sanitary. Further, blood sensor 24 and blood collection needle 26are replaced together every test, so that there is no fear that needleis used several times and there is no threat of infection.

FIG. 4 is a diagrammatic perspective assembly view of an example of theblood sampling cartridge. In FIG. 4, blood sensor 24 that examinessampled blood is attached to one end 23 a of holder 23. The outersurface of holder 23 has the shape of a cross, and connectors 27 formedwith conductive metal (in the blood test apparatus) are led betweencross-shaped convex parts 23 c. The shape of the outer surface of holder23 is not particularly limited and may be a regular polygon.

The other end of holder 23 has convex parts 23 d formed integrated withconvex parts 23 c, and convex parts 23 d have holes 23 e.

Lancet 25 is inserted into holder 23. Guides 25 c for preventing reuse,which are arranged 180 degrees apart from each other, are formedintegrated with lancet 25. Further, guides 25 d for improving linearmobility are provided between guides 25 c 180 degrees apart from eachother and slide inside holes 23 e provided in convex parts 23 d ofholder 23. Grip part 25 f is provided between convex parts 25 e providednear one end 25 a of lancet 25 and one end 25 a.

Further, fixing claw 23 f that fixes lancet 25 inserted into holder 23,is provided. Fixing claw 23 f can rotate with respect to holder 23 andhas supporting part 23 g for the rotation. Fixing claw 23 f is a resinelastic member that performs seesaw operation and releases the fixing oflancet 25 after blood sampling cartridge 22 is attached to cylinder body21 a (described above).

FIG. 5A is a cross-sectional view of blood sampling cartridge 22 uponpuncturing, and FIG. 5B is a cross-sectional view of blood samplingcartridge 22 when puncturing is finished. In a state shown in FIG. 5A,blood collection needle 26 projects from blood sensor 24. Convex part 25e of lancet 25 is latched at latch part 23 f provided at the other end23 b of holder 23, and so needle 26 does not project from blood sensor24.

In FIG. 5B, blood collection needle 26 is accommodated in holder 23 andstays. The bases of guides 25 c of lancet 25 are latched at latch part23 f provided at the other end 23 b of holder 23 and stay. Therefore,lancet 25 does not fall off from holder 23.

In the state shown in FIG. 5B, blood sampling cartridge 22 is removedfrom cylinder body 21 a. Even if lancet 25 is pushed in the direction ofarrow 35, guides 25 c run onto convex parts 23 c from holes 23 e ofholder 23 by their elasticity. The bases of guides 25 c are engaged atthe ends of holes 23 e and stay. Therefore, blood collection needle 26does not project again from blood sensor 24 and is secure. Further,needle 26 does not project and so the patient does not feel fear.

FIG. 6 is a diagrammatic perspective view of blood sampling cartridge22. As shown in FIG. 6, the height of cross-shaped convex part 23 cformed on the one end 23 a side of holder 23 is higher than the heightof cross-shaped convex part 23 d formed on the other end 23 b side ofholder 23. That is, the convex part 23 d side of holder 23 is thinnerthan the convex part 23 c side. In this way, if the front part of bloodsampling cartridge 22 with respect to the insertion direction is thinnerthan the rear part, blood sampling cartridge 22 can be inserted tocylinder body 21 a in a simple manner. Further, tip part 23 g (on theend 23 b side) of convex part 23 d on the other end 23 b side projectsat an acute angle. This is important to make sure that a connector(described later) formed on the cylinder body 21 a side contacts with adesired position of the blood sensor.

The whole of blood sampling cartridge 22 can be attached to and removedfrom cylinder body 21 a, and so needle 26 and blood sensor 24 can befreely attached to and removed from cylinder body 21 a together.Therefore, blood sensor 24 and needle 26 can be attached and replaced ina simple manner.

FIG. 7 is a cross-sectional view of an example of the blood sensor inthe blood test apparatus of the present invention. Blood sensor 24 hassubstrate 41, spacer 47 pasted on the upper surface of substrate 41, andcover 48 pasted on the upper surface of spacer 47. Hole 41 c provided insubstrate 41 and hole 47 c provided in spacer 47 form blood storing part49. Supply channel 47 d is connected to storing part 49. The tip ofsupply channel 47 d communicates with air hole 48 c.

Detecting section 40 arranged in supply channel 47 d includes detectionelectrodes as described later. The detecting section detects the inflowof blood and the blood components. Further, reagent 50 is placed on atleast part of detecting section 40. Reagent 50 is, for example, preparedby dropping on detecting section 40 formed on substrate 41, a reagentsolution prepared by adding and dissolving PQQ-GDH (0.1 to 5.0 U/bloodsensor), potassium ferricyanide (10 to 200 mM), maltitol (1 to 50 mM)and taurine (20 to 200 mM) in a 0.01 to 2.0 wt % aqueous solution ofCMC, and drying the reagent solution.

FIG. 8 is an exploded plan view of blood sensor 24. Blood sensor 24 hascover 48 shown in FIG. 8A, spacer 47 shown in FIG. 8B and substrate 41shown in FIG. 8C.

FIG. 8C is a plan view of substrate 41. Although substrate 41 is anoctagon, the shape of the substrate is not particularly limited. Thesize may be adjusted as appropriate, and, for example, one dimension 41a is set 9 mm, and the other dimension 41 b is set 8 mm. Material ofsubstrate 41 is preferably resin such as polyethylene terephthalate(PET), and its thickness preferably falls in a range of 0.075 to 0.25 mm(preferably 0.188 mm).

On one surface of substrate 41 (the surface that is pasted with spacer47), detection electrodes 42 to 45 and connection electrodes 42 a to 45a connected to detection electrodes 42 to 45, respectively, are formedin an integrated manner. Detection electrodes 42 to 45 and connectionelectrodes 42 a to 45 a can be formed by forming a conductive layerusing the sputtering method or the vapor deposition method, using gold,platinum, palladium as materials and applying laser machining to thisconductive layer. Hole 41 c is provided in substrate 41, and itsdiameter may be approximately 2.0 mm. Hole 41 c is preferably providedin approximately the center of substrate 41.

FIG. 8B is a plan view of spacer 47. Spacer 47 has the shape of anapproximate cross, but may be a polygon (preferably a regular polygon).If the spacer has the shape of a cross, connectors (not shown) can bearranged in its dent easily. The size of spacer 47 may be adjustedaccording to the size of substrate 41, and, for example, one dimension47 a may be 9 mm, and the other dimension 47 b may be 8 mm. Thethickness of spacer 47 may fall in a range of 0.05 to 0.15 mm(preferably 0.1 mm).

Hole 47 c is provided in spacer 47, and is in the position correspondinghole 41 c which is provided in approximately the center of substrate 41.The diameter of hole 47 c may be made the same (approximately 2.0 mm) asthe diameter of hole 41 c. Slit 47 d is formed in the direction fromhole 47 c to cross-shaped first convex part 47 e and corresponds theblood supply channel. Although the cavity of supply channel 47 d may beset approximately 0.144 μL by setting the width of the groove of slit 47d 0.6 mm and setting the length in the flow channel direction 2.4 mm,the size may be adjusted as appropriate. In this way, test can beperformed with a small amount of blood, so that the load on the patientbecomes small, and the patient does not feel fear. The material ofspacer 47 may be resin such as polyethylene terephthalate (PET).

FIG. 8A is a plan view of cover 48. The shape and size of cover 48 maybe made the same as those of spacer 47. Air hole 48 c is provided incross-shaped first convex part 48 d so as to correspond the tip part ofsupply channel 47 d. Preferably, the diameter of air hole 48 c isapproximately 50 μm.

The material of cover 48 is plastic, and preferably polyethyleneterephthalate. The thickness of cover 48 may fall in a range of 0.05 to0.25 mm (preferably 0.075 mm). The reverse side of cover 48corresponding to the ceiling part of supply channel 47 d is preferablysubjected to hydrophilicity treatment to make the blood sampled instoring part 49 smoothly flow in supply channel 47 d by capillaryaction. Further, the reverse side of cover 48 corresponding to theceiling part of hole 47 c is preferably subjected to water-repellencytreatment. Still further, the surface of cover 48 (the reverse side ofthe surface pasted with the spacer) is preferably subjected towater-repellency treatment.

FIG. 9 is a perspective plan view of blood sensor 24. Detectionelectrodes 42 to 45 are formed on substrate and configure a detectingsection. Detection electrodes 42 to 45 function as, for example, aworking electrode, a sensing electrode, a counter electrode and an Hctelectrode, respectively. The “working electrode” refers to an electrodefor measuring blood components, the “sensing electrode” refers to anelectrode for sensing whether or not blood is supplied to the detectingsection, the “counter electrode” refers to a counterpart electrode ofthe working electrode, and the “Hct electrode” refers to an electrodefor measuring the hematocrit level in blood. Detection electrodes 42 to45 are connected to relevant connection electrodes 42 a to 45 a,respectively, and connection electrodes 42 a to 45 a are arranged alongthe outer periphery of substrate 41.

The reagent contacts with at least part of detecting section 40 onsubstrate 41. The reagent is preferably arranged in contact withdetection electrode 42, which functions as a working electrode, anddetection electrode 44, which functions as a counter electrode. On theother hand, the reagent is preferably not arranged in contact withdetection electrode 45, which functions as an Hct electrode.

The blood flowing out from the skin punctured with blood collectionneedle 26 is guided into storing part 49. The blood guided into storingpart 49 flows in supply channel 47 d by capillary action, is led intodetecting section 40, and reacts with regent 50 in detecting section 40.The result of the reaction is led to connection electrodes 42 a, 43 a,44 a and 45 a connected to the detection electrodes.

Further, the result of the reaction is led to terminals (33 a, 33 b, 33c and 33 d, not shown) formed at cylinder body 21 a via connectors (27a, 27 b, 27 c and 27 d, not shown) which contact with connectionelectrodes 42 a, 43 a, 44 a and 45 a, and, further, the result of thereaction is led to measuring circuit 32 from the terminals.

As shown in FIG. 9, connection electrodes 42 a to 45 a have contactparts 42 b to 45 b, respectively, to contact with the connectors.Contact parts 42 b, 43 b, 44 b and 45 b contact with connectors 27 a, 27b, 27 c and 27 d, respectively. Contact parts 42 b, 43 b, 44 b and 45 bare preferably arranged around a specific point so as to surround thespecific point and arranged at equiangular intervals centered on thespecific point.

The “specific point” is preferably provided in storing part 49 (insidehole 41 c) on the surface of the substrate, and, more preferably, nearthe center of storing part 49. Further, the “specific point” may beprovided on the axis where puncturing needle 26 moves, on the surface ofthe substrate. Still further, the specific point is preferably providednear the center of the rotation about the axis of the insertiondirection for attaching the blood sampling cartridge to the attachingpart, of the blood sampling cartridge. Further, contact parts 42 b to 45b are preferably arranged at approximately the same distance from thespecific point.

In this way, connectors 27 of the blood test apparatus contact withblood sensor 24 at equiangular intervals centered on the specific point,so that the connectors and the blood sensor can be connected adequatelyregardless of the angle at which the blood sampling cartridge isattached. Therefore, the blood sampling cartridge can be attached moreeasily.

If contact parts 42 b, 43 b, 44 b and 45 b are arranged at equiangularintervals centered on the specific point, when blood sampling cartridge22 is attached to cylinder body 21 a and the contact parts contact withthe connectors, all the contact parts can contact with one of theconnectors even if the rotation angle with respect to the axis of theinsertion direction of the blood sampling cartridge is arbitrary. On theother hand, it is not clear which connectors contact with which contactparts. Therefore, to insert the blood sampling cartridge casuallyregardless of the rotation angle with respect to the axis of theinsertion direction, a “reference electrode” is preferably provided forspecifying which contact parts of the connection electrodes contact withwhich connectors.

FIG. 10 shows an example where blood sensor 24 has a referenceelectrode. Blood sensor 24 a shown in FIG. 10 has the “referenceelectrode” for specifying the positions of the connection electrodes, inone of the connection electrodes, in addition to connection electrodes42 a to 45 a. Blood sensor 24 a may be the same as blood sensor 24 shownin FIG. 9 except that the reference electrode is provided. The referenceelectrode shown in FIG. 10 is reference contact part 43 c, which is theposition that contacts with the connector. Reference contact part 43 cis provided in connection electrode 43 a together with contact part 43b, that is, contact part 43 b and reference contact part 43 c areconnected via a conductor. Therefore, the resistance between contactpart 43 b and reference contact part 43 c is zero. Reference contactpart 43 c may be provided in one of connection electrodes 42 a to 45 aand is not limited to connection electrode 43 a.

Contact parts 42 b to 45 b and reference contact part 43 c arepreferably provided near the outer periphery of blood sensor 24 a,arranged around the specific point and arranged at equiangular intervalscentered on the specific point. Therefore, five connectors 27 ofcylinder body 21 a are provided at equiangular intervals centered on thespecific point so as to correspond contact parts 42 b to 45 b andreference contact part 43 c, respectively. Preferably, blood samplingcartridge holder 23 including blood sensor 24 a does not have the crossshape shown in FIG. 2, but has a star shape or the shape of a pentagon.Connectors 27 arranged in the attaching part of the test apparatus arearranged at the same angle around the star-shaped or pentagon-shapedholder.

By providing reference contact part 43 c in addition to contact parts 42a to 45 b, even if blood sampling cartridge 22 is inserted into cylinderbody 21 a at an arbitrary rotation angle with respect to the axis of theinsertion direction, (A) one of the connectors can contact with one ofthe contact parts or the reference contact part, and (B) measuringcircuit 32 can detect neighboring electrodes where the electricalresistance is zero, specify connection electrodes including thereference contact part, specify the positions of connection electrodes42 a to 45 a, and further specify the functions of the detectionelectrodes connected to the connection electrodes.

FIG. 11 shows an example of the flow of the test using blood testapparatus 20. In attaching step 60, blood sampling cartridge 22 isinserted into cylinder body 21 a. By the insertion, holder 23 of bloodsampling cartridge 22 is latched at slider 37, and grip part 25 f oflancet 25 is held by holding part 30 a of plunger 30.

In step 61, blood sensor 24 of blood sampling cartridge 22 is pressedagainst the part to be punctured (the skin of the patient) and forcedback into opening part 21 b. As a result, slider 37 presses mechanicalswitch 38-1 to the first position.

In step 62, the negative pressure means starts to start negativepressure operation and creates a negative pressure in cylinder body 21a. When mechanical switch 38-1 is pressed to the first position, thenegative pressure means preferably starts automatically.

In step 63, the locking mechanism formed by latch convex part 31 cprovided in handle 31 and latch concave part 21 d provided in housing21, is released. The locking mechanism is preferably released after thenegative pressure means is driven for a predetermined period, becausethe part to be punctured is plumped up and can be punctured easily. Asdescribed above, the part to be punctured is plumped up, and thereby theblood sensor may be further forced into opening part 21 b, and slider 37may press mechanical switch 38-1 to the second position. By displayingthat mechanical switch 38-1 is pressed to the second position on displaysection 75, it is possible to make the timing of releasing the lockingmechanism more appropriate. Further, the locking mechanism may bereleased automatically after mechanical switch 38-1 is pressed to thesecond position.

In step 64, blood collection needle 26 is propelled toward the skin ofthe part to be punctured via lancet 25 which interlocks with plunger 30urged by the spring, and punctures the skin. In next step 65, bloodcollection needle 26 is moved backward in blood sampling cartridge 22.

In step 66, blood is sampled. The blood flowing out from the partpunctured with blood collection needle 26, is guided into storing part49 of blood sensor 24. The blood in storing part 49 flows into supplychannel 47 d by capillary action and is led to detecting section 40.Further, the negative pressure facilitates the inflow of blood to supplychannel 47 d. When the blood led to detecting section 40 reachesdetection electrode 43 as a sensing electrode, detecting section 40determines that the amount of blood required for measurement isobtained. In this way, detecting section 40 of the blood sensordetermines whether or not enough blood is obtained. Therefore, it is notnecessary to over-sample blood, so that the load on the patient isreduced significantly. Further, by stopping driving of the negativepressure means after the determination, it is possible to prevent powerof the battery from wasting.

In step 67, glucose is measured. After the glucose in blood and reagent50 (containing a glucose oxidation-reduction enzyme) placed on detectingsection 40 are reacted for a certain period, a voltage is appliedbetween detection electrode 42 as a working electrode and detectionelectrode 44 as a counter electrode. The mediator in a reductioncondition, produced on detection electrode 42 by enzyme reaction, isoxidized, and its oxidation current is detected. The glucose and theglucose oxidation-reduction enzyme are normally reacted for one to tenseconds. Generally, the voltage applied in step 67 is 0.2 to 0.5 V andthe time the voltage is applied is one to five seconds. The time thevoltage is applied is measured by timer 79 (described later).

In step 68, the hematocrit (Hct) level is measured. A voltage is appliedbetween detection electrode 45 as a working electrode and detectionelectrode 42 as a counter electrode. By this means, a current dependingon the Hct level can be detected, and the Hct level is measured based onthe detected current. The measured Hct level is used for correction inglucose measurement. The Hct level calculated from the calibration curvecreated in advance, of the current and the Hct level, may be used forcorrection. Further, the detected current may be used as is.

Generally, the voltage applied in step 68 is 2 to 3 V, and the time thevoltage is applied is 0.01 to 5 seconds. In step 68, the reagent doesnot contact with detection electrode 45 which is the working electrode,there is a certain interval between detection electrode 45 and detectionelectrode 42, and only blood exists in this interval, so that anoxidation current that is not influenced by reagent 50 and that dependson the Hct level can be detected.

In step 69, blood components are corrected. That is, using the Hct levelmeasured in step 68, the glucose content calculated in step 67 iscorrected. This correction is performed based on the calibration curve(including a calibration table) created in advance. The correctedglucose content is displayed on display section 75 in blood testapparatus 20 in step 70 as a final measurement result after correction.

Used blood sampling cartridge 22 after going through steps 67, 68 and 69of blood sugar level measurement, is replaced every measurement.

FIG. 12 is a block diagram of blood test apparatus 20. Blood testapparatus 20 shown in FIG. 12 has blood sensor 24 a shown in FIG. 9.

Terminals 33 a to 33 e in FIG. 12 are connected with connectionelectrodes 42 a to 45 a (in this case, 43 a includes a referenceelectrode and has two connection parts) of blood sensor 24 a via theconnectors. Terminals 33 a to 33 e are connected to switch circuit 71,and the output of switch circuit 71 is connected to the input ofcurrent/voltage converter 72. The output of converter 72 is connected tothe input of calculating section 74 via analogue/digital converter(hereinafter A/D converter) 73. The output of calculating section 74 isconnected to display section 75 (for example, a liquid crystal display).Further, reference voltage supply 78 is connected to switch circuit 71.Reference voltage supply 78 may be a ground potential.

The output of controlling section 76 is connected to a control terminalof switch circuit 71, calculating section 74, transmitting section 77and timer 79. Further, the output of calculating section 74 is alsoconnected to the input of transmitting section 77. The output ofcontrolling section 76 is connected to negative pressure means 82 (forexample, a vacuum generator), and the output of negative pressure means82 communicates with the interior of cylinder body 21 a via negativepressure path 83. Therefore, negative pressure means 82 can create anegative pressure inside cylinder body 21 a. Further, the output ofsensing means 38 (such as mechanical switch 38-1) is connected tocontrolling section 76, and controlling section 76 starts or stopsnegative pressure means 82 based on this output.

The operation of blood test apparatus 20 will be described. First, whenblood sensor 24 (which may be blood sampling cartridge 22 includingblood sensor 24) is attached to cylinder body 21 a, the apparatus ispowered on.

Before the blood test, when the blood sensor is blood sensor 24 a, thefollowing operation is performed. That is, to which of terminals 33 a to33 e connection electrodes 42 a to 45 a are connected, is specified. Bya command from controlling section 76, out of terminals 33 a to 33 e, aterminal where resistance with the neighboring terminal is zero, isspecified. The connection electrode connected to the specified terminalwhere the resistance with the neighboring terminal is zero, isdetermined to be connection electrode 43 a. Using one of terminals 33 ato 33 e connected to connection electrode 43 a as a reference, otherterminals 33 are determined as terminals connected to connectionelectrodes 44 a, 45 a and 42 a, in that order. In this way, afterterminals 33 connected to connection electrodes 42 a to 45 a aredetermined, blood is examined. When blood sensor 24 (see FIG. 8) nothaving a reference electrode, is used, terminals 33 to be connected toconnection electrodes 42 a to 45 a are determined in advance, and sothis operation for the determining the connection electrodes is notnecessary, and the steps are started from the following operation.

Switch circuit 71 is switched, and connection electrode 42 a ofdetection electrode 42 as a working electrode for measuring the amountof blood components is connected to current/voltage converter 72 viaterminal 33 b. Further, connection electrode 43 a of detection electrode43 which serves as a sensing electrode for detecting the inflow of bloodis connected to reference voltage supply 78 via terminal 33 d. A certainvoltage is applied between detection electrode 42 and detectionelectrode 43, and the apparatus enters a standby state.

In this standby state, when information that the skin of the part to bepunctured is placed in an appropriate position is outputted tocontrolling section 76 from sensing means 38, controlling section 76starts negative pressure means 82. After a predetermined period passes,lancet 25 is driven and puncturing is performed. Sensing means 38 mayreport to controlling section 76 that the skin of the part to bepunctured is plumped up by a negative pressure. Controlling section 76may display it on display section 75.

If blood from the punctured part flows into blood sensor 24 a, a currentflows between detection electrodes 42 and 43. This current is convertedto a voltage by current/voltage converter 72, and the voltage value isconverted to a digital value by A/D converter 73. The digital value isoutputted to calculating section 74. Calculating section 74 detects theinflow of blood based on the digital value. After the inflow of blood isdetected, driving of negative pressure means 82 is stopped.

Next, glucose, which is a blood component, is measured. The glucosecontent is measured through the following steps. First, by the commandof controlling section 76, switch circuit 71 is switched, and detectionelectrode 42, which serves as a working electrode in glucose contentmeasurement, is connected to current/voltage converter 72 via terminal33 b. Further, detection electrode 44, which serves as a counterelectrode in glucose content measurement, is connected to referencevoltage supply 78 via terminal 33 e.

While the glucose in blood and the oxidation-reduction enzyme arereacted for a certain period, current/voltage converter 72 and referencevoltage supply 78 may be turned off, and, after a certain period (lessthan 10 seconds) passes, a certain voltage (0.2 to 0.5 V) may be appliedbetween detection electrodes 42 and 44 by a command from controllingsection 76. The current flowing between detection electrodes 42 and 44is converted to a voltage by current/voltage converter 72. The convertedvoltage value is converted to a digital value by A/D converter 73 andoutputted to calculating section 74. Calculating section 74 converts thedigital value to a glucose content.

After the glucose content is measured, the Hct level is measured. TheHct level is measured through the following steps. First, by a commandfrom controlling section 76, switch circuit 71 is switched, anddetection electrode 45, which serves as a working electrode formeasuring the Hct level, is connected to current/voltage converter 72via terminal 33 a. Further, detection electrode 42, which serves as acounter electrode for measuring the Hct level, is connected to referencevoltage supply 78 via terminal 33 b.

Then, by a command from controlling section 76, a certain voltage (2 to3 V) is applied between detection electrodes 45 and 42 fromcurrent/voltage converter 72 and reference voltage supply 78. Thecurrent flowing between detection electrodes 45 and 42 is converted to avoltage by current/voltage converter 72, and the voltage value isconverted to a digital value by A/D converter 73 and outputted tocalculating section 74. Calculating section 74 converts the digitalvalue to an Hct level.

Using the measured Hct level and the glucose content, and, withreference to the calibration curve or the calibration table, the glucosecontent is corrected with the Hct level. The corrected result isdisplayed on display section 75.

Further, the corrected result may be transmitted from transmittingsection 77 to an injection apparatus that injects insulin (used as anexample of an antidote). The result may be transmitted by radio but ispreferably transmitted using optical communication which does notinterfere with medical equipment. If the injection apparatus can set thedose of insulin automatically based on the measured result transmittedfrom transmitting section 77, the patient does not have to set the doseof insulin. Further, the dose of insulin can be set to the injectionapparatus without involving an artificial means, so that it is possibleto prevent setting errors.

Further, switch 38 is provided in cylinder body 21 a and pressed byslider 37. Unless blood sensor 24 (which may be blood sampling cartridge22 with blood sensor 24) is attached and forced into the attaching partand slider 37 is moved, negative pressure means 82 does not start.Therefore, negative pressure means 82 does not operate by error.

As described above, sensing means 38 may be mechanical switch 38-1, anelectrical sensor or an optical sensor. Mechanical switch 38-1 ispressed when the part to be punctured of the patient, pressed againstthe blood sensor of the blood test apparatus, contacts with tip part 21b of cylinder body 21 a.

As described above, according to the blood test apparatus and blood testmethod of the present invention, it is possible to detect a contactbetween the apparatus and the skin of the patient and drive a negativepressure means automatically according to the detected output.Therefore, even when the patient holds the apparatus with one hand andperforms test, the patient can hold the apparatus stably and performmeasurement reliably. By releasing plunger 30 automatically after theskin is plumped up, it is possible to make the operation performed bythe patient simple and realize more reliable measurement.

INDUSTRIAL APPLICABILITY

According to the blood test apparatus and blood test method of thepresent invention, it is possible to alleviate the load of the bloodtest on the patient. That is, to sample blood for test in the bloodsensor, by pressing the blood sensor of the apparatus against the skinof the part to be punctured, a negative pressure means starts withoutspecial operation. Blood from the punctured part can be sampled in theblood sensor in a simple manner. Therefore, the present invention iswidely applicable to medical equipment.

1. A blood test apparatus comprising: a housing with an opening; aplunger that moves back and forth inside the housing, the plunger havinga projecting member; a fixing member configured to fix the plunger,which is provided in the housing; a blood sampling cartridge, in which ablood sensor, a puncturer, and a holder that holds the blood sensor andthe puncturer, are integrated, the blood sampling cartridge beingremovably attached to the opening, the puncturer including a lancet, oneend of the lancet is held by the plunger, and a blood collection needleattached to an other end of the lancet; and a measuring circuit thatmeasures a signal obtained from the blood sensor to analyze componentsin the blood; wherein, when the blood sampling cartridge is attached tothe opening of the housing, the projecting member of the plunger isengaged with the fixing member, such that the plunger is fixed with thefixing member.
 2. The blood test apparatus according to claim 1, furthercomprising a button provided on an outer surface of the housing, andwhen the button is pressed, the plunger is fixed with the fixing member.3. The blood test apparatus according to claim 1, wherein: a holdingmember is provided in the plunger, and a grip is provided at the one endof the lancet, and when the blood sampling cartridge is attached to theopening of the housing, the holding member holds the grip.
 4. The bloodtest apparatus according to claim 1, wherein the puncturer and the bloodsensor in the blood sampling cartridge attached to the opening, aremovable relative to each other.
 5. The blood test apparatus according toclaim 1, further comprising a slider provided in the housing, whereinthe slider is slidable in the housing, and is urged toward the openingby a pressing spring.
 6. The blood test apparatus according to claim 5,wherein: the lancet of the blood sampling cartridge attached to theopening is driven by the plunger, and the blood sensor and the holder ofthe blood sampling cartridge attached to the opening interlock with theslider and move in and out of the housing through the opening.
 7. Theblood test apparatus according to claim 1, further comprising a fixingclaw that fixes the lancet, the fixing claw being provided in the holderof the blood sampling cartridge, wherein, when the blood samplingcartridge is attached to the opening of the housing, the fixing clawreleases the lancet.
 8. The blood test apparatus according to claim 7,wherein: when the blood sampling cartridge is attached to the opening ofthe housing, an end of the slider presses the fixing claw, such that thefixing claw releases the lancet.
 9. The blood test apparatus accordingto claim 7, wherein: when the blood sampling cartridge is attached tothe opening of the housing, an end of the slider presses the fixing clawto allow the fixing claw to rotate, such that the fixing claw releasesthe lancet.